Preventing buried oxide gouging during planar and finfet processing on soi

ABSTRACT

A method for preventing damage to the insulator layer of a semiconductor device during creation of fin field effect transistor (FinFET) includes obtaining a material stack having an active semiconductor layer, an insulator layer, and an etch stop layer between the active semiconductor layer and the insulator layer; forming a fin-array from the active semiconductor layer; patterning the fin-array; and fabricating a FinFET device from the patterned fin-array; where the etch stop layer is resistant to processes the etch stop layer is exposed to during the forming, patterning, and fabricating operations, such that the etch stop layer and the insulator layer are not damaged during the forming, patterning, and fabricating operations.

DOMESTIC PRIORITY

This application is a continuation of and claims priority to U.S.Non-Provisional patent application Ser. No. 15/142,145, filed Apr. 29,2016, entitled “PREVENTING BURIED OXIDE GOUGING DURING PLANAR AND FINFETPROCESSING ON SOI,” which is a divisional of and claims priority to U.S.Non-Provisional patent application Ser. No. 14/603,624, filed on Jan.23, 2015, entitled “A STRUCTURE FOR PREVENTING BURIED OXIDE GOUGINGDURING PLANAR AND FINFET PROCESSING ON SOI,” which claims priority toU.S. Provisional Patent Application No. 61/987,671, filed on May 2,2014, entitled “STRUCTURE AND METHOD TO PREVENT BURIED OXIDE GOUGINGDURING PLANAR AND FINFET PROCESSING ON SOI.”

BACKGROUND

The present invention relates generally to semiconductor andmicroelectronic structures and methods for fabricating these structures.More particularly, the invention relates to methods, and structures,which prevent the insulator layer from being damaged during the creationof fin field effect transistor devices.

The use of a semiconductor fin-type field effect transistor (FinFET) hasbeen found to provide many benefits to microelectronic devices. FinFETsallow an increase in transistor density, an improvement in theelectrical characteristics of individual transistors, and advancement inthe overall performance of microelectronic devices. However, theprocesses used for the manufacture of fins for FINFET devices havepresented a number of difficulties that adversely affect the physicaland electrical performance of the resulting FinFET device.

During fabrication of a FinFET, a material stack is formed usingprocesses known in the art to layer selected materials one on top of theother. Typically, a material stack intended for FinFET fabricationincludes at least a substrate layer, an insulator layer and an activesemiconductor layer. During manufacture of a FinFET from a materialstructure, a plurality of fins are formed from the material stack byapplying processes, such as those known in the art as etches and cleans,to the active semiconductor layer. These processes are utilized to forma plurality of vertical semiconductor structures from the activesemiconductor layer. The resulting vertical semiconductor structures arethe individual fins for FinFET devices. A plurality of fins is oftenreferred to as a fin-array, which is typically then patterned byapplying further processes known in the art to remove un-needed fins.Typically the processes utilized are selected based on the chemical andphysical properties of the processes, as well as the chemical andphysical properties of the materials included in the material stack.

The processes used in the fabrication of fins for FinFET devices haveproved capable of providing both benefits for, and defects in, theresulting fin structures. For example, processes utilized to pattern afin-array can result in gouging the insulator layer due to the chemicalproperties of the processes used and the chemical composition of theinsulator layer. Gouging typically creates irregular topography on thesurface of the insulator layer. The presence of irregularities on thesurface of the insulator layer has been found to greatly increase thelikelihood of voids forming during subsequent material depositions. Andthe presence of voids has been known to result in the degradation of theelectrical properties and obstruction of the performance of theresulting microelectronic device.

Gouging, however, is not the only problem that results when processes,such as etches and cleans, remove some of the insulator layer. Processesutilized to prepare for gate dielectric formation can also remove someof the insulator layer, thereby undercutting the fin due to theinteraction between the chemical makeup of the insulator layer and theunique chemistry of the processes. Undercutting is often the result ofapplying etches and cleans during the formation of a gate over a fin ofa FinFET, which may involve etching away semiconducting material orother material applied during manufacturing processes. Undercutting iscapable of improving gate control, but can also undermine fin stabilityand introduce defects into the resulting FinFET structure. Undercuttinghas been found to cause physically weaker connections between the finand the underlying layer, which can fatally reduce the stability of theaffected fin to the point of physical failure. Undercutting can alsocreate difficulties for subsequently removing material that becomesdeposited within the undercut region, and such deposited material cansignificantly alter the affected fins electrical performance, such ascausing gate to gate electrical shorts.

SUMMARY

Embodiments of the present invention provide a method for preventingdamage to the insulator layer of a semiconductor device during thecreation of a fin field effect transistor (FinFET) device. The methodincludes obtaining a material stack having an active semiconductorlayer, an insulator layer, and an etch stop layer existing between theactive semiconductor layer and the insulator layer; forming a fin-arrayfrom the active semiconductor layer by applying fin-array formationprocesses to the material stack, with the etch stop layer resistant to aprocess of the fin-array formation processes that the etch stop layer isexposed to, such that the etch stop layer and the insulator layer arenot damaged during fin-array formation; patterning the fin-array byapplying fin-array patterning processes after the fin-array has beenformed from the active semiconductor layer, with the etch stop layerresistant to a process of the fin-array patterning processes that theetch stop layer is exposed to, such that the etch stop layer and theinsulator layer are not damaged during fin-array patterning; andfabricating a FinFET device by applying FinFET fabrication processesafter the fin-array has been patterned by the fin-array patterningprocesses, with the etch stop layer resistant to a process of the FinFETfabrication processes that the etch stop layer is exposed to, such thatthe etch stop layer and the insulator layer are not damaged duringFinFET fabrication.

Embodiments of the present invention also provide a structure, forcreating a semiconductor device without damaging the insulator layerduring creation of fin field effect transistor devices. The structureincludes: an insulator layer; an active semiconductor layer; an etchstop layer existing between the insulator layer and the activesemiconductor layer and being of material resistant to processes thatthe etch stop layer is exposed to during creation of a FinFET havingfins formed from the active semiconductor layer, such that the etch stoplayer and the insulator layer are not damaged during creation of theFinFET.

Embodiments of the present invention further provide a structure, forcreating a semiconductor device without damaging the insulator layerduring creation of fin field effect transistor devices. The structureincludes: an insulator layer; a patterned fin-array of activesemiconductor material; an etch stop layer existing between theinsulator layer and the patterned fin-array, and being of materialresistant to processes that the etch stop layer was exposed to duringformation and patterning of the patterned fin-array as well as processesthat the etch stop layer will be exposed to during fabrication of aFinFET device having a fin of the patterned fin-array, such that theetch stop layer and the insulator layer are not damaged during processesfor formation, patterning and fabrication.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a conventional material stack prior to application offin-array formation processes.

FIG. 2 shows a conventional material stack after fin-array formationprocesses have been applied to create a fin-array with the addition of amask layer.

FIG. 3 shows a fin-array with additional mask layer after furthermaterial layers have been deposited in preparation for the applicationof processes to pattern the fin-array.

FIG. 4 shows a fin-array and additional mask layer after some of theprocesses for patterning the fin-array have uncovered the unneeded fins.

FIG. 5 shows a conventional material stack after a fin-array has beenformed and patterned resulting in a patterned fin-array having gougingat the insulator layer surface.

FIG. 6 show a conventional material stack after a fin-array has beenformed, patterned and subject to processes applied for gate formation,resulting in a patterned fin-array having gouging at the insulator layersurface and undercutting at interface of the fins and insulator layer.

FIG. 7 shows an embodiment of the present invention prior to applicationof processes for forming a fin-array.

FIG. 8 shows an embodiment of the present invention after fin-arrayformation processes have been applied to create a fin-array with anadditional mask layer.

FIG. 9 shows an embodiment of the present invention after materials havebeen deposited in preparation for application of processes to patternthe fin-array.

FIG. 10 shows an embodiment of the present invention after some of theprocesses for patterning the fin-array have uncovered the unneeded fins.

FIG. 11 shows an embodiment of the present invention after the processesfor forming and patterning a fin-array have been applied and is alsorepresentative of a formed and patterned fin-array that has hadprocesses applied for gate formation.

FIG. 12 shows an embodiment of the present invention prior toapplication of process for forming a fin-array, which involves anadditional material layer to increase electrical properties of theresulting semiconductor devices.

FIG. 13 shows an embodiment of the present invention after the processfor forming and patterning a fin-array have been applied, which involvesan additional material layer to increase the electrical properties ofthe resulting semiconductor devices.

DETAILED DESCRIPTION

In view of the above, embodiments of the present invention address theabove described deficiencies by a method and apparatuses capable ofpreventing the insulator layer from being damaged during the creation ofFinFET devices.

It will be readily understood that the components of the presentinvention, as generally described and illustrated in the figures herein,may be arranged and designed in a variety of different configurations inaddition to the described presently preferred embodiments. Thus, thefollowing detailed description of the embodiments of the presentinvention, as represented in the figures, is not intended to limit thescope of the invention, as claimed, but is merely representative ofselected presently preferred embodiments of the invention. The followingdescription is intended only by way of example, and simply illustratescertain selected presently preferred embodiments of the invention asclaimed herein.

Implementations consistent with the present invention provide apatterned array of FinFET fins for FinFET applications, that has beenformed using a material stack that employs a non-sacrificial etch stoplayer to prevent gouging and undercutting. In one aspect of theinvention a material stack is obtained having at least an activesemiconductor layer separated from an insulator layer by at least anetch stop layer. Subsequent processes conventionally known in the art,such as etches and cleans, are applied to the material stack to form afin-array without damaging the insulator layer. Further processesconventionally known in the art are applied to the material stack thathas been formed into a fin-array such that the fin-array is patterned toremove unneeded fins without damaging the insulator layer.

Accordingly, the material that forms the etch stop layer possessessufficient properties such that the processes that will be applied tothe material stack to form and pattern one or more vertical structures,such as fins, from the active semiconductor layer will not result indamaging the insulator layer. And the material that forms the etch stoplayer possesses sufficient properties such that further processesapplied to the fins to create FinFET devices will not result inundercutting the fins.

As is known in the art, one or more patterned photo-resist layers can beused as etch masks to pattern and etch the active semiconductor layer toform and pattern a plurality of vertical semiconductor fin structures.Furthermore, the fin structures may be etched using any conventionaletch process, including but not limited to, anisotropic etchingprocesses such as reactive ion etching or the like. Thereafter,depending on the final design implementation, the resulting patternedfin-array may be used to fabricate one or more FinFET devices.

The materials used in the method and apparatuses described herein maycomprise materials with appropriate etch selectivity properties or otherappropriate properties and are not limited to those materialsspecifically referenced herein. Accordingly, various wet and dry etchescan be used in the processes describe herein to remove any portion ofthe material stack, or to remove any portion of additional materiallayers that may be required, and such etches can possess chemistriessuitable for creating the patterned fin-array while leaving theinsulator layer undamaged due to the chemical composition of the etchstop layer.

FIGS. 1-5 illustrate, in cross section, the initial operations in aprocess conventionally known in the art for creating a FinFET devicefrom a silicon on insulator (SOI) wafer with particular attention givento the processes conducted for fabrication of a patterned fin-array.

Referring to FIG. 1, a conventional semiconductor material stack 14 isillustrated as an example of the prior art. The material stack includesa substrate layer 11, an insulator layer 12, and an active semiconductorlayer 13. As is known in the art, a SOI material stack can be used. Astypical for a SOI material stack a layer of silicon is provided as thesubstrate layer 11, a buried oxide layer (BOX) of silicon oxide (SiO₂)is provided as the insulator layer 12, and another layer of silicon (Si)is provided as the active semiconductor layer 13.

As is known in the art, the semiconductor layer can be any semiconductormaterial, either doped or undoped, including but not limited to silicon,silicon germanium, germanium, silicon carbide, a III-V compoundsemiconductor, a II-VI compound semiconductor, a carbon-basedsemiconductor such as a carbon nanotube or graphene, an organicsemiconductor, or any multilayer or other combination of these.Similarly, the substrate and insulator layers are also not limited tothose materials specifically stated in the prior art example.

Referring to FIG. 2, the material stack 14 as shown in FIG.1 isillustrated as having been processed into a fin-array 23 of a pluralityof fins 21. As applied in the prior art to an SOI wafer, the processesresult in silicon fins 21 that are in contact with the insulator layer12 of SiO₂, having been etched from the active semiconductor layer 13 ofSi using conventional vertical semiconductor device fabricationprocesses known in the art, such as reaction ion etching (RIE). As isknown in the art, this processing can be accomplished utilizing a spacerimage transfer technique and, as a result of the processes applied, thesilicon fins 21 are shown as having been capped with a fin hard masklayer 22. In the example of an SOI wafer, the fin hard mask layer 22 maytypically be SiO₂ or SiN. As is know in the art, various etching andcleaning processes may be applied to the material stack 14 to form aplurality of fins 21 that makeup a fin-array 23.

Referring to FIG. 3, the fin-array 23 as shown in FIG. 2, is illustratedas having had various layers of additional materials deposited byfurther semiconductor device fabrication processes known in the art asneeded to prepare the fin-array 23 for patterning processes. Patterningis typically accomplished by removing any un-needed fins 34. In theprior art the additional layers as typically being applied to an SOIwafer for example are an optical planarization layer (OPL) 31, a siliconantireflective coating (SiARC) layer 32, and a patterned photoresistlayer 33. The patterned photoresist layer is used as part of thepatterning process by exposing the OPL 31 and SiARC layer 32 toconventional vertical anisotropic etching processes, such as a tri-layerlitho open process. As is know in the art, various processes andmaterials may be applied to the material stack 14 to form and pattern afin-array 23.

Referring to FIG. 4, the unneeded fins 34 with additional fin hard maskcap 22, which need to be removed in order to create the intendedpatterned fin-array, have been uncovered by applying conventionalanisotropic etching processes to the additional layers in order toselectively remove the additional layers from the area of the unneededfins 34. In the prior art example utilizing an SOI wafer, an OPL layer31, and an SiARC layer 32, reactive ion etching (RIE) may be used tocomplete this process.

Referring to FIG. 5, multiple processes known in the art have beenapplied to remove the uncovered fin, and the additional layers, to forma patterned fin-array 52. In this example utilizing a SOI wafer theprocesses resulted in SiARC layer burnoff, OPL strip, hard mask etch,and removal of the uncovered Si fins. However, because of the chemicalmakeup of the insulator layer 12, such as silicon oxide, and thechemical properties of the processes used, such as reactive ion etching,the insulator layer has been etched as well. Etching of the insulatorlayer has resulted in visible damage to the topography of the insulatorlayer, such as gouging 51 of the insulator layer 12.

Referring to FIG. 6, additional processes known in the art have beenapplied to accomplish gate formation (not shown) as part of fabricatingFinFET devices from the patterned fin-array 52, and some of theseadditional processes have resulted in undercut 61 to develop at theinterface of the fin 21 and insulator 12. In this example that utilizesa SOI wafer, some of the processes applied to accomplish gate formationhad chemical properties such that insulator layer 12 was partiallyremoved, which resulting in furthering the gouges 51 and developingundercut 61 at the fin 21 and insulator layer 12 interface. Specificexamples of such processes known in the art include cleaning prior toepitaxy growth at the source drain area and cleaning prior to gatedielectric formation. During epitaxy growth, SiGe or Si epitaxy usuallyis used to merge a fin outside of gate and spacer. However, epitaxygrowth requires a cleaning operation be performed first. This pre-cleanoperation will typically etch oxide materials, such as the insulatorbetween and under fins. Furthermore, before a gate dielectric is formed,a multi-step cleaning process is needed to clean the fin surface. Suchfin surface cleaning will expose the insulator material to processesthat will also etch oxide materials, such as the insulator between andunder fins.

The resulting damage described as occurring during the processes in theprior art for patterned fin-array formation and preparation for epitaxygrowth and gate formation (not shown) are sought to be prevented by thepresent invention. Advantages and features of the present invention willbecome readily apparent to those skills in the art from the followingdetailed descriptions. The embodiments shown and describe provideillustration of preferred methods and structures for enabling thoseskilled in the art to carry out the present invention. The invention iscapable of modifications in various respects, all without departing fromthe invention. Accordingly, the figures are to be regarded asillustrative in nature, and not restrictive.

FIGS. 7-11 illustrate, in cross-section, initial operations for creatinga FinFET device from a material stack, exemplifying a preferredembodiment of the present invention concerning methods and apparatusesimplemented during creation of a patterned fin-array without incurringdamage known in the art to result from applying conventional processesto a material stack to create a FinFET device.

Referring to FIG. 7, an embodiment of the present invention isillustrated as a material stack 72 that includes an insulator layer 12,an active semiconductor layer 13, and an etch stop layer 71 interposedbetween them such that the etch stop layer is in contact with the activesemiconductor layer 13 and the insulator layer 12. The etch stop layer71 may have various thicknesses based on the desired application,preferably within the range of about 0 and 50 nanometers. The etch stoplayer 71 is made of material having properties, for example a materialhaving a high-k value, such that neither the insulator layer 12 nor etchstop layer 71 will be damaged by processes that the insulator layer 12would otherwise be exposed to during the creation of a patternedfin-array and formation of gate. In accordance with an embodiment of thepresent invention, a method for preventing damage to the insulator layer12 of a semiconductor device during creation of fin field effecttransistor devices includes obtaining a material stack 72 including atleast an active semiconductor layer 13, an insulator layer 12, and anetch stop layer 71 existing between the active semiconductor layer 13and the insulator layer 12.

In a preferred embodiment the insulator layer 12 is silicon oxide(SiO₂), the active semiconductor layer 13 is silicon (Si), and the etchstop layer 71 is hafnium oxide (HfO₂). The insulator layer 12 is incontact with the etch stop layer 71, and the etch stop layer 71 is alsoin contact with the active semiconductor layer 13, such that theinsulator layer 12 and the active semiconductor layer 13 are not incontact. The etch stop layer 71 of HfO₂ can be added through processesknown in the art, such as thermal growth or deposition, during waferbonding typically utilized to create a conventional SOI wafer. The etchstop layer 71 has a preferred thickness of 5 nanometers. However, otherembodiments are capable of being made such that the etch stop layer isnot limited to HfO₂ or a thickness of 5 nanometers, and can be made ofother materials that are not susceptible to degradation, or destruction,by the processes, such as etches and cleans, that the insulator layerwould other wise be exposed to. Some other such materials that couldform the etch stop layer are, but not limited to, Al₂O₃, ZrO₃, La₂O₃,and HfSiO_(x).

Referring to FIG. 8, the material stack 72 has had conventional etchprocesses known in the art applied in order to create fins 21 from theactive semiconductor layer 13. Multiple fins 21 exist across the etchstop layer 71, forming a fin-array 81. In accordance with an embodimentof the present invention, a method for preventing damage to theinsulator layer of a semiconductor device during creation of a fin fieldeffect transistor device includes forming a fin-array 81 from the activesemiconductor layer 13 by applying processes to the material stack 72and the etch stop layer is resistant to those processes of the fin-arrayformation processes that the etch stop layer 71 is exposed to, such thatthe etch stop layer 71 and the insulator layer 12 are not damaged duringformation of the fin-array 81.

In a preferred embodiment, the active semiconductor layer 13 is made ofsilicon and is subjected to the conventional process of spacer imagetransfer techniques as are known in the art. The active semiconductorlayer 13 of silicon is processed into silicon fins 21, capped with ahard mask layer 22 of either silicon oxide (SiO₂) or silicon nitride(SiN). The silicon fins 21 are in contact with the etch stop layer 71 ofHfO₂ and form a fin-array 81 of silicon fins 21. The etch stop layer 71and the insulator layer 12 are not damaged by the processes utilized toform the fin-array 81 from the active semiconductor layer 13.

Referring to FIG. 9, the fin-array 81 as shown in FIG. 8, is illustratedas having had various layers of additional layers of material 31, 32,33, deposited by further semiconductor device fabrication processes,known in the art, as needed to prepare the fin-array 81 to be patternedby removing any of the fins 21 that are un-needed fins 34.

In a preferred embodiment the additional layers are an opticalplanarization layer (OPL) 31, a silicon antireflective coating (SiARC)layer 32, and a patterned photoresist layer 33. The patternedphotoresist layer is utilized in part of the patterning process forexposing the OPL layer 31 and SiARC layer 32 to conventional verticalanisotropic etching processes, such as a tri-layer litho open process.

Referring to FIG. 10, the unneeded fins 34 of fin-array 81 have beenuncovered by applying conventional anisotropic etching processes to theadditional layers 31, 32 and 33, as part of the process for patterningthe fin-array 81 without damaging the insulator layer 12 or the etchstop layer 71. In accordance with an embodiment of the presentinvention, a method for preventing damage to the insulator layer of asemiconductor device during creation of a fin field effect transistordevice includes patterning the fin-array 81 by applying patterningprocesses to the material stack 72 and the etch stop layer 71 isresistant to those processes of the patterning processes that the etchstop layer 71 is exposed to, such that the etch stop layer 71 and theinsulator 12 are not damaged during patterning of the fin-array 81.

In a preferred embodiment exposing the unneeded fins 34 throughselective removal of the SiARC layer 32 and the OPL layer 33 can beachieved utilizing reactive ion etching (RIE).

Referring to FIG. 11, multiple processes known in the art have beenapplied to remove the uncovered fin, and the additional layers 31, 32,and 33, as well as the hard mask caps 22, to form a patterned fin-array111 without damaging the insulator layer 12 or the etch stop layer 71.In accordance with an embodiment of the present invention, a method forpreventing damage to the insulator layer 12 of a semiconductor deviceduring creation of a fin field effect transistor device includespatterning the fin-array 81 by applying patterning processes to thematerial stack 72 and the etch stop layer 71 is resistant to thoseprocesses of the patterning processes that the etch stop layer 71 isexposed to, such that the etch stop layer 71 and the insulator 12 arenot damaged during patterning of the fin-array 71.

In a preferred embodiment the applied processes resulted in SiARC layer32 burnoff, OPL layer 31 strip, hard mask 22 etch, and removal of theuncovered fins. Any process, or combination of processes, known in theart may be used, including but not limited to, reactive ion etching(RIE), ashing, and wet etching. However, the processes capable of beingutilized are those having a chemistry suitable for removing theadditional layers 31, 32, 33 and unneeded fins 34, such that the etchstop layer 71 of HfO₂ is able to resist the processes and prevent theinsulator layer 12 of SiO₂ from being damaged. For example, SiARC layer32 burnoff and fin hard mask 22 etching stop on the etch stop layer 61.Similarly, cutting of the unneeded fins 34, preferably through reactiveion etching, stops on the etch stop layer 71, OPL layer 31 ashing stopson the etch stop layer 71, and stripping of the hard mask layer 22,which is on the fins 21 forming the patterned fin-array 81, by wet ordry etching also stops on the etch stop layer 71. Unlike in the priorart, the processes utilized to remove all unneeded fins 34 andadditional material layers of photo-resist mask 33, Si Arc 32, and OPL31, did no reach the insulator layer 12 of SiO₂ and stopped at the etchstop layer 71 of HfO₂. As such, gouging the insulator layer 12 of SiO₂was prevented by employing a non-sacrificial etch-stop layer 71.

Furthermore, additional processes known in the art will likely beapplied to accomplish gate formation (not shown) as part of fabricatingFinFET devices, and some of these additional processes can result inundercut to develop at the interface of the fin 21 and insulator 12. Inaccordance with an embodiment of the present invention, a method forpreventing damage to the insulator layer 12 of a semiconductor deviceduring creation of a fin field effect transistor device includesfabricating a FinFET device by applying processes to the patternedfin-array 111 and the etch stop layer 71 is resistant to those processesof the FinFET fabricating processes that the etch stop layer 71 isexposed to, such that the etch stop layer 71 and the insulator 12 arenot damaged during patterning of the fin-array 71.

In a preferred embodiment, the processes applied to accomplish gateformation have chemical properties that the etch stop layer 71 isresistant to. As a result insulator layer 12 is not partially removeddue to gate formation processes and developing undercut at the fin 21and insulator layer 12 interface does not occur, such that the fin 21insulator layer 12 interface remains as shown in FIG. 11. As such,undercutting the fins 21 is prevented by including a non-sacrificialetc-stop layer 71 possessing desired material properties in the materialstack.

FIGS. 12-13 illustrate another embodiment of the present inventioninvolving an interfacial layer for improving the electrical propertiesof the resulting semiconductor devices.

Referring to FIG. 12, another embodiment is presented as a materialstack 122 having an interfacial layer 121 between the activesemiconductor layer 13 and the etch stop layer 71. The interfacial layermay be desired in order to improve the electrical property of theinterface between the resulting fins and the layer of material the finsare in contact with, shown as interfacial layer 121. In order to improvethe electrical property of the interface, the interfacial layer 121should be of a material having electrical properties similar to theinsulator layer 12, such as SiO₂. Furthermore, it is preferred that theinterfacial layer 121 be of substantially thin thickness, so that anyresulting undercut will be limited to the thickness of the interfaciallayer 121, which would be a significant improvement to the prior art andas such likely result in an improvement in fin stability and electricalperformance. The material and thickness of the interfacial layer 121 mayvary depending on the desired result, however the preferred thickness isapproximately 1 nanometer.

Referring to FIG. 13, an embodiment of the present invention isillustrated having interfacial layer 121 between the patterned fin-array131 and the etch stop layer 71. The undercut 132 resulting from cleans,known in the art to be applied in preparation for epitaxy growth andgate formation, is substantially less than the undercut as would haveresulted in the prior art, for comparison see undercut 51 as shown inFIG. 5, because the interfacial layer 121 is sufficiently thin enough tosubstantially reduces the resulting undercut 132.

From the foregoing, it is to be appreciated that FinFET devices may beformed having undamaged insulator layers and no undercut. Such FinFETdevices may be fabricated in fewer processing operations by replacingprocesses and utilizing other semiconductor device fabricationtechniques and materials, while utilizing the core elements of thepresent invention to prevent the insulator layer from being damaged andprevent undercuts from developing.

While at least one preferred embodiment has been presented in theforegoing detailed description of the invention it should be appreciatedthat a vast number of variations exist. It should also be appreciatedthat the exemplary embodiments are only examples, and are not intendedto limit the scope, applicability, or configuration of the invention inany way. Rather, the foregoing detailed description will enable thoseskilled in the art to implement the invention, it being understood thatvarious changes may be made in the selection and arrangement ofprocesses and elements described without departing from the scope of theinvention as set forth in the claims and their legal equivalents.

1. A method for preventing damage to the insulator layer of a semiconductor device during fabrication of fin field effect transistor (FinFET) devices, the method comprising: obtaining a material stack comprising an active semiconductor layer, an insulator layer, and an etch stop layer existing between the active semiconductor layer and the insulator layer; forming a fin-array from the active semiconductor layer by applying fin-array formation processes to the material stack, with the etch stop layer resistant to those fin-array formation processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during fin-array formation; patterning the fin-array by applying fin-array patterning processes after the fin-array has been formed from the active semiconductor layer, with the etch stop layer resistant to those fin-array patterning processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during fin-array patterning; and fabricating a FinFET device by applying FinFET fabrication processes after the fin-array has been patterned by the fin-array patterning processes, with the etch stop layer resistant to those FinFET fabrication processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during FinFET fabrication.
 2. The method of claim 1, wherein the material stack further comprises an interfacial layer between the active semiconductor layer and the etch stop layer.
 3. The method of claim 2, wherein the interfacial layer comprises a material similar to the insulator layer material.
 4. The method of claim 1, wherein the etch stop layer comprises hafnium oxide (HfO₂).
 5. The method of claim 1, wherein the etch stop layer comprises aluminum oxide (Al₂O₃).
 6. The method of claim 1, wherein the etch stop layer comprises zirconate (ZrO₃).
 7. The method of claim 1, wherein the etch stop layer comprises lanthanum oxide (La₂O₃).
 8. The method of claim 1, wherein the insulator layer comprises silicon dioxide.
 9. The method of claim 1, wherein the fin-array formation process comprises reactive ion etching.
 10. The method of claim 1, wherein the fin-array formation process comprises anisotrophic etching.
 11. A method for preventing damage to the insulator layer of a semiconductor device during fabrication of fin field effect transistor (FinFET) devices, the method comprising: obtaining a material stack comprising an active semiconductor layer, an insulator layer, and an etch stop layer existing between and contacting both the active semiconductor layer and the insulator layer, the etch-stop layer comprising a high-k material; forming a fin-array from the active semiconductor layer by applying fin-array formation processes to the material stack, with the etch stop layer resistant to those fin-array formation processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during fin-array formation; patterning the fin-array by applying fin-array patterning processes after the fin-array has been formed from the active semiconductor layer, with the etch stop layer resistant to those fin-array patterning processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during fin-array patterning; and fabricating a FinFET device by applying FinFET fabrication processes after the fin-array has been patterned by the fin-array patterning processes, with the etch stop layer resistant to those FinFET fabrication processes that the etch stop layer is exposed to, such that the etch stop layer and the insulator layer are not damaged during FinFET fabrication.
 12. The method of claim 11, wherein the material stack further comprises an interfacial layer between the active semiconductor layer and the etch stop layer.
 13. The method of claim 12, wherein the interfacial layer comprises a material similar to the insulator layer material.
 14. The method of claim 11, wherein the etch stop layer comprises hafnium oxide (HfO₂).
 15. The method of claim 11, wherein the etch stop layer comprises aluminum oxide (Al₂O₃).
 16. The method of claim 11, wherein the etch stop layer comprises zirconate (ZrO₃).
 17. The method of claim 11, wherein the etch stop layer comprises lanthanum oxide (La₂O₃).
 18. The method of claim 11, wherein the insulating layer comprises silicon dioxide.
 19. The method of claim 11, wherein the fin-array formation process comprises reactive ion etching.
 20. The method of claim 11, wherein the fin-array formation process comprises anisotrophic etching. 